aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/croaring/README.md
blob: 0f938004c975067325551e0a7b1cd81230daaa48 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
# CRoaring

[![Ubuntu-CI](https://github.com/RoaringBitmap/CRoaring/actions/workflows/ubuntu-noexcept-ci.yml/badge.svg)](https://github.com/RoaringBitmap/CRoaring/actions/workflows/ubuntu-noexcept-ci.yml) [![VS17-CI](https://github.com/RoaringBitmap/CRoaring/actions/workflows/vs17-ci.yml/badge.svg)](https://github.com/RoaringBitmap/CRoaring/actions/workflows/vs17-ci.yml)
[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/croaring.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:croaring)

[![Doxygen Documentation](https://img.shields.io/badge/docs-doxygen-green.svg)](http://roaringbitmap.github.io/CRoaring/)



Portable Roaring bitmaps in C (and C++) with full support for your favorite compiler (GNU GCC, LLVM's clang, Visual Studio, Apple Xcode, Intel oneAPI). Included in the [Awesome C](https://github.com/kozross/awesome-c) list of open source C software.

# Introduction

Bitsets, also called bitmaps, are commonly used as fast data structures. Unfortunately, they can use too much memory.
 To compensate, we often use compressed bitmaps.

Roaring bitmaps are compressed bitmaps which tend to outperform conventional compressed bitmaps such as WAH, EWAH or Concise.
They are used by several major systems such as [Apache Lucene][lucene] and derivative systems such as [Solr][solr] and
[Elasticsearch][elasticsearch], [Metamarkets' Druid][druid], [LinkedIn Pinot][pinot], [Netflix Atlas][atlas], [Apache Spark][spark], [OpenSearchServer][opensearchserver], [Cloud Torrent][cloudtorrent], [Whoosh][whoosh], [InfluxDB](https://www.influxdata.com), [Pilosa][pilosa], [Bleve](http://www.blevesearch.com), [Microsoft Visual Studio Team Services (VSTS)][vsts], and eBay's [Apache Kylin][kylin]. The CRoaring library is used in several systems such as [Apache Doris](http://doris.incubator.apache.org), [ClickHouse](https://github.com/ClickHouse/ClickHouse), [Redpanda](https://github.com/redpanda-data/redpanda), and [StarRocks](https://github.com/StarRocks/starrocks). The YouTube SQL Engine, [Google Procella](https://research.google/pubs/pub48388/), uses Roaring bitmaps for indexing.

We published a peer-reviewed article on the design and evaluation of this library:

- Roaring Bitmaps: Implementation of an Optimized Software Library, Software: Practice and Experience 48 (4), 2018 [arXiv:1709.07821](https://arxiv.org/abs/1709.07821)

[lucene]: https://lucene.apache.org/
[solr]: https://lucene.apache.org/solr/
[elasticsearch]: https://www.elastic.co/products/elasticsearch
[druid]: http://druid.io/
[spark]: https://spark.apache.org/
[opensearchserver]: http://www.opensearchserver.com
[cloudtorrent]: https://github.com/jpillora/cloud-torrent
[whoosh]: https://bitbucket.org/mchaput/whoosh/wiki/Home
[pilosa]: https://www.pilosa.com/
[kylin]: http://kylin.apache.org/
[pinot]: http://github.com/linkedin/pinot/wiki
[vsts]: https://www.visualstudio.com/team-services/
[atlas]: https://github.com/Netflix/atlas

Roaring bitmaps are found to work well in many important applications:

> Use Roaring for bitmap compression whenever possible. Do not use other bitmap compression methods ([Wang et al., SIGMOD 2017](http://db.ucsd.edu/wp-content/uploads/2017/03/sidm338-wangA.pdf))


[There is a serialized format specification for interoperability between implementations](https://github.com/RoaringBitmap/RoaringFormatSpec/). Hence, it is possible to serialize a Roaring Bitmap from C++, read it in Java, modify it, serialize it back and read it in Go and Python.

# Objective

The primary goal of the CRoaring is to provide a high performance low-level implementation that fully take advantage
of the latest hardware. Roaring bitmaps are already available on a variety of platform through Java, Go, Rust... implementations. CRoaring is a library that seeks to achieve superior performance by staying close to the latest hardware.


(c) 2016-... The CRoaring authors.



# Requirements

- Linux, macOS, FreeBSD, Windows (MSYS2 and Microsoft Visual studio).
- We test the library with ARM, x64/x86 and POWER processors. We only support little endian systems (big endian systems are vanishingly rare).
- Recent C compiler supporting the C11 standard (GCC 7 or better, LLVM 8 or better (clang), Xcode 11 or better, Microsoft Visual Studio 2022 or better, Intel oneAPI Compiler 2023.2 or better), there is also an optional C++ class that requires a C++ compiler supporting the C++11 standard.
- CMake (to contribute to the project, users can rely on amalgamation/unity builds if they do not wish to use CMake).
- The CMake system assumes that git is available.
- Under x64 systems, the library provides runtime dispatch so that optimized functions are called based on the detected CPU features. It works with GCC, clang (version 9 and up) and Visual Studio (2017 and up). Other systems (e.g., ARM) do not need runtime dispatch.

Hardly anyone has access to an actual big-endian system. Nevertheless,
We support big-endian systems such as IBM s390x through emulators---except for
IO serialization which is only supported on little-endian systems (see [issue 423](https://github.com/RoaringBitmap/CRoaring/issues/423)).


# Quick Start

The CRoaring library can be amalgamated into a single source file that makes it easier
for integration into other projects. Moreover, by making it possible to compile
all the critical code into one compilation unit, it can improve the performance. For
the rationale, please see the [SQLite documentation](https://www.sqlite.org/amalgamation.html),
or the corresponding [Wikipedia entry](https://en.wikipedia.org/wiki/Single_Compilation_Unit).
Users who choose this route, do not need to rely on CRoaring's build system (based on CMake).

We offer amalgamated files as part of each release.

Linux or macOS users might follow the following instructions if they have a recent C or C++ compiler installed and a standard utility (`wget`).


 1. Pull the library in a directory
    ```
    wget https://github.com/RoaringBitmap/CRoaring/releases/download/v2.1.0/roaring.c
    wget https://github.com/RoaringBitmap/CRoaring/releases/download/v2.1.0/roaring.h
    wget https://github.com/RoaringBitmap/CRoaring/releases/download/v2.1.0/roaring.hh
    ```
 2. Create a new file named `demo.c` with this content:
    ```C
    #include <stdio.h>
    #include <stdlib.h>
    #include "roaring.c"
    int main() {
        roaring_bitmap_t *r1 = roaring_bitmap_create();
        for (uint32_t i = 100; i < 1000; i++) roaring_bitmap_add(r1, i);
        printf("cardinality = %d\n", (int) roaring_bitmap_get_cardinality(r1));
        roaring_bitmap_free(r1);

        bitset_t *b = bitset_create();
        for (int k = 0; k < 1000; ++k) {
                bitset_set(b, 3 * k);
        }
        printf("%zu \n", bitset_count(b));
        bitset_free(b);
        return EXIT_SUCCESS;
    }
    ```
 2. Create a new file named `demo.cpp` with this content:
    ```C++
    #include <iostream>
    #include "roaring.hh" // the amalgamated roaring.hh includes roaring64map.hh
    #include "roaring.c"
    int main() {
        roaring::Roaring r1;
        for (uint32_t i = 100; i < 1000; i++) {
            r1.add(i);
        }
        std::cout << "cardinality = " << r1.cardinality() << std::endl;

        roaring::Roaring64Map r2;
        for (uint64_t i = 18000000000000000100ull; i < 18000000000000001000ull; i++) {
            r2.add(i);
        }
        std::cout << "cardinality = " << r2.cardinality() << std::endl;
        return 0;
    }
    ```
 2. Compile
    ```
    cc -o demo demo.c
    c++ -std=c++11 -o demopp demo.cpp
    ```
 3. `./demo`
    ```
    cardinality = 900
    1000
    ```
 4. `./demopp`
    ```
    cardinality = 900
    cardinality = 900
    ```


# Using Roaring as a CPM dependency


If you like CMake and CPM, you can add just a few lines in your `CMakeLists.txt` file to grab a `CRoaring` release. [See our CPM demonstration for further details](https://github.com/RoaringBitmap/CPMdemo).



```CMake
cmake_minimum_required(VERSION 3.10)
project(roaring_demo
  LANGUAGES CXX C
)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_C_STANDARD 11)

add_executable(hello hello.cpp)
# You can add CPM.cmake like so:
# mkdir -p cmake
# wget -O cmake/CPM.cmake https://github.com/cpm-cmake/CPM.cmake/releases/latest/download/get_cpm.cmake
include(cmake/CPM.cmake)
CPMAddPackage(
  NAME roaring
  GITHUB_REPOSITORY "RoaringBitmap/CRoaring"
  GIT_TAG v2.0.4
  OPTIONS "BUILD_TESTING OFF"
)

target_link_libraries(hello roaring::roaring)
```


# Using as a CMake dependency with FetchContent

If you like CMake, you can add just a few lines in your `CMakeLists.txt` file to grab a `CRoaring` release. [See our demonstration for further details](https://github.com/RoaringBitmap/croaring_cmake_demo_single_file).

If you installed the CRoaring library locally, you may use it with CMake's `find_package` function as in this example:

```CMake
cmake_minimum_required(VERSION 3.15)

project(test_roaring_install VERSION 0.1.0 LANGUAGES CXX C)

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)


set(CMAKE_C_STANDARD 11)
set(CMAKE_C_STANDARD_REQUIRED ON)

find_package(roaring REQUIRED)

file(WRITE main.cpp "
#include <iostream>
#include \"roaring/roaring.hh\"
int main() {
  roaring::Roaring r1;
  for (uint32_t i = 100; i < 1000; i++) {
    r1.add(i);
  }
  std::cout << \"cardinality = \" << r1.cardinality() << std::endl;
  return 0;
}")

add_executable(repro main.cpp)
target_link_libraries(repro PUBLIC roaring::roaring)
```


# Amalgamating

To generate the amalgamated files yourself, you can invoke a bash script...

```bash
./amalgamation.sh
```

If you prefer a silent output, you can use the following command to redirect ``stdout`` :

```bash
./amalgamation.sh > /dev/null
```


(Bash shells are standard under Linux and macOS. Bash shells are available under Windows as part of the  [GitHub Desktop](https://desktop.github.com/) under the name ``Git Shell``. So if you have cloned the ``CRoaring`` GitHub repository from within the GitHub Desktop, you can right-click on ``CRoaring``, select ``Git Shell`` and then enter the above commands.)

It is not necessary to invoke the script in the CRoaring directory. You can invoke
it from any directory where you want the amalgamation files to be written.

It will generate three files for C users: ``roaring.h``, ``roaring.c`` and ``amalgamation_demo.c``... as well as some brief instructions. The ``amalgamation_demo.c`` file is a short example, whereas ``roaring.h`` and ``roaring.c`` are "amalgamated" files (including all source and header files for the project). This means that you can simply copy the files ``roaring.h`` and ``roaring.c`` into your project and be ready to go! No need to produce a library! See the ``amalgamation_demo.c`` file.

# API

The C interface is found in the files

- [roaring.h](https://github.com/RoaringBitmap/CRoaring/blob/master/include/roaring/roaring.h),
- [roaring64.h](https://github.com/RoaringBitmap/CRoaring/blob/master/include/roaring/roaring64.h).

We also have a C++ interface:

- [roaring.hh](https://github.com/RoaringBitmap/CRoaring/blob/master/cpp/roaring.hh),
- [roaring64map.hh](https://github.com/RoaringBitmap/CRoaring/blob/master/cpp/roaring64map.hh).


# Dealing with large volumes

Some users have to deal with large volumes of data. It  may be important for these users to be aware of the `addMany` (C++) `roaring_bitmap_or_many` (C) functions as it is much faster and economical to add values in batches when possible. Furthermore, calling periodically the `runOptimize` (C++) or `roaring_bitmap_run_optimize` (C) functions may help.


# Running microbenchmarks

We have microbenchmarks constructed with the Google Benchmarks.
Under Linux or macOS, you may run them as follows:

```
cmake -B build -D ENABLE_ROARING_MICROBENCHMARKS=ON
cmake --build build
./build/microbenchmarks/bench
```

By default, the benchmark tools picks one data set (e.g., `CRoaring/benchmarks/realdata/census1881`).
We have several data sets and you may pick others:

```
./build/microbenchmarks/bench benchmarks/realdata/wikileaks-noquotes
```

You may disable some functionality for the purpose of benchmarking. For example, assuming you
have an x64 processor, you could benchmark the code without AVX-512 even if both your processor
and compiler supports it:

```
cmake -B buildnoavx512 -D ROARING_DISABLE_AVX512=ON -D ENABLE_ROARING_MICROBENCHMARKS=ON
cmake --build buildnoavx512
./buildnoavx512/microbenchmarks/bench
```

You can benchmark without AVX or AVX-512 as well:

```
cmake -B buildnoavx -D ROARING_DISABLE_AVX=ON -D ENABLE_ROARING_MICROBENCHMARKS=ON
cmake --build buildnoavx
./buildnoavx/microbenchmarks/bench
```

# Custom memory allocators
For general users, CRoaring would apply default allocator without extra codes. But global memory hook is also provided for those who want a custom memory allocator. Here is an example:
```C
#include <roaring.h>

int main(){
    // define with your own memory hook
    roaring_memory_t my_hook{my_malloc, my_free ...};
    // initialize global memory hook
    roaring_init_memory_hook(my_hook);
    // write you code here
    ...
}
```

By default we use:
```C
static roaring_memory_t global_memory_hook = {
    .malloc = malloc,
    .realloc = realloc,
    .calloc = calloc,
    .free = free,
    .aligned_malloc = roaring_bitmap_aligned_malloc,
    .aligned_free = roaring_bitmap_aligned_free,
};
```

We require that the `free`/`aligned_free` functions follow the C
convention where `free(NULL)`/`aligned_free(NULL)` have no effect.


# Example (C)


This example assumes that CRoaring has been build and that you are linking against the corresponding library. By default, CRoaring will install its header files in a `roaring` directory. If you are working from the amalgamation script, you may add the line `#include "roaring.c"` if you are not linking against a prebuilt CRoaring library and replace `#include <roaring/roaring.h>` by `#include "roaring.h"`.

```c
#include <roaring/roaring.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

bool roaring_iterator_sumall(uint32_t value, void *param) {
    *(uint32_t *)param += value;
    return true;  // iterate till the end
}

int main() {
    // create a new empty bitmap
    roaring_bitmap_t *r1 = roaring_bitmap_create();
    // then we can add values
    for (uint32_t i = 100; i < 1000; i++) roaring_bitmap_add(r1, i);
    // check whether a value is contained
    assert(roaring_bitmap_contains(r1, 500));
    // compute how many bits there are:
    uint32_t cardinality = roaring_bitmap_get_cardinality(r1);
    printf("Cardinality = %d \n", cardinality);

    // if your bitmaps have long runs, you can compress them by calling
    // run_optimize
    uint32_t expectedsizebasic = roaring_bitmap_portable_size_in_bytes(r1);
    roaring_bitmap_run_optimize(r1);
    uint32_t expectedsizerun = roaring_bitmap_portable_size_in_bytes(r1);
    printf("size before run optimize %d bytes, and after %d bytes\n",
           expectedsizebasic, expectedsizerun);

    // create a new bitmap containing the values {1,2,3,5,6}
    roaring_bitmap_t *r2 = roaring_bitmap_from(1, 2, 3, 5, 6);
    roaring_bitmap_printf(r2);  // print it

    // we can also create a bitmap from a pointer to 32-bit integers
    uint32_t somevalues[] = {2, 3, 4};
    roaring_bitmap_t *r3 = roaring_bitmap_of_ptr(3, somevalues);

    // we can also go in reverse and go from arrays to bitmaps
    uint64_t card1 = roaring_bitmap_get_cardinality(r1);
    uint32_t *arr1 = (uint32_t *)malloc(card1 * sizeof(uint32_t));
    assert(arr1 != NULL);
    roaring_bitmap_to_uint32_array(r1, arr1);
    roaring_bitmap_t *r1f = roaring_bitmap_of_ptr(card1, arr1);
    free(arr1);
    assert(roaring_bitmap_equals(r1, r1f));  // what we recover is equal
    roaring_bitmap_free(r1f);

    // we can go from arrays to bitmaps from "offset" by "limit"
    size_t offset = 100;
    size_t limit = 1000;
    uint32_t *arr3 = (uint32_t *)malloc(limit * sizeof(uint32_t));
    assert(arr3 != NULL);
    roaring_bitmap_range_uint32_array(r1, offset, limit, arr3);
    free(arr3);

    // we can copy and compare bitmaps
    roaring_bitmap_t *z = roaring_bitmap_copy(r3);
    assert(roaring_bitmap_equals(r3, z));  // what we recover is equal
    roaring_bitmap_free(z);

    // we can compute union two-by-two
    roaring_bitmap_t *r1_2_3 = roaring_bitmap_or(r1, r2);
    roaring_bitmap_or_inplace(r1_2_3, r3);

    // we can compute a big union
    const roaring_bitmap_t *allmybitmaps[] = {r1, r2, r3};
    roaring_bitmap_t *bigunion = roaring_bitmap_or_many(3, allmybitmaps);
    assert(
        roaring_bitmap_equals(r1_2_3, bigunion));  // what we recover is equal
    // can also do the big union with a heap
    roaring_bitmap_t *bigunionheap =
        roaring_bitmap_or_many_heap(3, allmybitmaps);
    assert(roaring_bitmap_equals(r1_2_3, bigunionheap));

    roaring_bitmap_free(r1_2_3);
    roaring_bitmap_free(bigunion);
    roaring_bitmap_free(bigunionheap);

    // we can compute intersection two-by-two
    roaring_bitmap_t *i1_2 = roaring_bitmap_and(r1, r2);
    roaring_bitmap_free(i1_2);

    // we can write a bitmap to a pointer and recover it later
    uint32_t expectedsize = roaring_bitmap_portable_size_in_bytes(r1);
    char *serializedbytes = malloc(expectedsize);
    // When serializing data to a file, we recommend that you also use
    // checksums so that, at deserialization, you can be confident
    // that you are recovering the correct data.
    roaring_bitmap_portable_serialize(r1, serializedbytes);
    // Note: it is expected that the input follows the specification
    // https://github.com/RoaringBitmap/RoaringFormatSpec
    // otherwise the result may be unusable.
    // The 'roaring_bitmap_portable_deserialize_safe' function will not read
    // beyond expectedsize bytes.
    // We recommend you further use checksums to make sure that the input is from
    // serialized data.
    roaring_bitmap_t *t = roaring_bitmap_portable_deserialize_safe(serializedbytes, expectedsize);
    if(t == NULL) { return EXIT_FAILURE; }
    const char *reason = NULL;
    if (!roaring_bitmap_internal_validate(t, &reason)) {
        return EXIT_FAILURE;
    }
    assert(roaring_bitmap_equals(r1, t));  // what we recover is equal
    roaring_bitmap_free(t);
    // we can also check whether there is a bitmap at a memory location without
    // reading it
    size_t sizeofbitmap =
        roaring_bitmap_portable_deserialize_size(serializedbytes, expectedsize);
    assert(sizeofbitmap ==
           expectedsize);  // sizeofbitmap would be zero if no bitmap were found
    // We can also read the bitmap "safely" by specifying a byte size limit.
    // The 'roaring_bitmap_portable_deserialize_safe' function will not read
    // beyond expectedsize bytes.
    // We recommend you further use checksums to make sure that the input is from
    // serialized data.
    t = roaring_bitmap_portable_deserialize_safe(serializedbytes, expectedsize);
    if(t == NULL) {
        printf("Problem during deserialization.\n");
        // We could clear any memory and close any file here.
        return EXIT_FAILURE;
    }
    // We can validate the bitmap we recovered to make sure it is proper.
    const char *reason_failure = NULL;
    if (!roaring_bitmap_internal_validate(t, &reason_failure)) {
        printf("safely deserialized invalid bitmap: %s\n", reason_failure);
        // We could clear any memory and close any file here.
        return EXIT_FAILURE;
    }
    // It is still necessary for the content of seriallizedbytes to follow
    // the standard: https://github.com/RoaringBitmap/RoaringFormatSpec
    // This is guaranted when calling 'roaring_bitmap_portable_deserialize'.
    assert(roaring_bitmap_equals(r1, t));  // what we recover is equal
    roaring_bitmap_free(t);

    free(serializedbytes);

    // we can iterate over all values using custom functions
    uint32_t counter = 0;
    roaring_iterate(r1, roaring_iterator_sumall, &counter);

    // we can also create iterator structs
    counter = 0;
    roaring_uint32_iterator_t *i = roaring_iterator_create(r1);
    while (i->has_value) {
        counter++;  // could use    i->current_value
        roaring_uint32_iterator_advance(i);
    }
    // you can skip over values and move the iterator with
    // roaring_uint32_iterator_move_equalorlarger(i,someintvalue)

    roaring_uint32_iterator_free(i);
    // roaring_bitmap_get_cardinality(r1) == counter

    // for greater speed, you can iterate over the data in bulk
    i = roaring_iterator_create(r1);
    uint32_t buffer[256];
    while (1) {
        uint32_t ret = roaring_uint32_iterator_read(i, buffer, 256);
        for (uint32_t j = 0; j < ret; j++) {
            counter += buffer[j];
        }
        if (ret < 256) {
            break;
        }
    }
    roaring_uint32_iterator_free(i);

    roaring_bitmap_free(r1);
    roaring_bitmap_free(r2);
    roaring_bitmap_free(r3);
    return EXIT_SUCCESS;
}
```

# Compressed 64-bit Roaring bitmaps (C)


We also support efficient 64-bit compressed bitmaps in C:

```c++
  roaring64_bitmap_t *r2 = roaring64_bitmap_create();
  for (uint64_t i = 100; i < 1000; i++) roaring64_bitmap_add(r2, i);
  printf("cardinality (64-bit) = %d\n", (int) roaring64_bitmap_get_cardinality(r2));
  roaring64_bitmap_free(r2);
```

The API is similar to the conventional 32-bit bitmaps. Please see
the header file `roaring64.h` (compare with `roaring.h`).

# Conventional bitsets (C)

We support convention bitsets (uncompressed) as part of the library.

Simple example:

```C
bitset_t * b = bitset_create();
bitset_set(b,10);
bitset_get(b,10);// returns true
bitset_free(b); // frees memory
```

More advanced example:

```C
bitset_t *b = bitset_create();
for (int k = 0; k < 1000; ++k) {
    bitset_set(b, 3 * k);
}
// We have bitset_count(b) == 1000.
// We have bitset_get(b, 3) is true
// You can iterate through the values:
size_t k = 0;
for (size_t i = 0; bitset_next_set_bit(b, &i); i++) {
    // You will have i == k
    k += 3;
}
// We support a wide range of operations on two bitsets such as
// bitset_inplace_symmetric_difference(b1,b2);
// bitset_inplace_symmetric_difference(b1,b2);
// bitset_inplace_difference(b1,b2);// should make no difference
// bitset_inplace_union(b1,b2);
// bitset_inplace_intersection(b1,b2);
// bitsets_disjoint
// bitsets_intersect
```

In some instances, you may want to convert a Roaring bitmap into a conventional (uncompressed) bitset.
Indeed, bitsets have advantages such as higher query performances in some cases. The following code
illustrates how you may do so:

```C
roaring_bitmap_t *r1 = roaring_bitmap_create();
for (uint32_t i = 100; i < 100000; i+= 1 + (i%5)) {
     roaring_bitmap_add(r1, i);
}
for (uint32_t i = 100000; i < 500000; i+= 100) {
     roaring_bitmap_add(r1, i);
}
roaring_bitmap_add_range(r1, 500000, 600000);
bitset_t * bitset = bitset_create();
bool success = roaring_bitmap_to_bitset(r1, bitset);
assert(success); // could fail due to memory allocation.
assert(bitset_count(bitset) == roaring_bitmap_get_cardinality(r1));
// You can then query the bitset:
for (uint32_t i = 100; i < 100000; i+= 1 + (i%5)) {
    assert(bitset_get(bitset,i));
}
for (uint32_t i = 100000; i < 500000; i+= 100) {
    assert(bitset_get(bitset,i));
}
// you must free the memory:
bitset_free(bitset);
roaring_bitmap_free(r1);
```

You should be aware that a convention bitset (`bitset_t *`) may use much more
memory than a Roaring bitmap in some cases. You should run benchmarks to determine
whether the conversion to a bitset has performance benefits in your case.

# Example (C++)


This example assumes that CRoaring has been build and that you are linking against the corresponding library. By default, CRoaring will install its header files in a `roaring` directory so you may need to replace `#include "roaring.hh"` by `#include <roaring/roaring.hh>`. If you are working from the amalgamation script, you may add the line `#include "roaring.c"` if you are not linking against a CRoaring prebuilt library.

```c++
#include <iostream>

#include "roaring.hh"

using namespace roaring;

int main() {
    Roaring r1;
    for (uint32_t i = 100; i < 1000; i++) {
        r1.add(i);
    }

    // check whether a value is contained
    assert(r1.contains(500));

    // compute how many bits there are:
    uint32_t cardinality = r1.cardinality();

    // if your bitmaps have long runs, you can compress them by calling
    // run_optimize
    uint32_t size = r1.getSizeInBytes();
    r1.runOptimize();

    // you can enable "copy-on-write" for fast and shallow copies
    r1.setCopyOnWrite(true);

    uint32_t compact_size = r1.getSizeInBytes();
    std::cout << "size before run optimize " << size << " bytes, and after "
              << compact_size << " bytes." << std::endl;

    // create a new bitmap with varargs
    Roaring r2 = Roaring::bitmapOf(5, 1, 2, 3, 5, 6);

    r2.printf();
    printf("\n");

    // create a new bitmap with initializer list
    Roaring r2i = Roaring::bitmapOfList({1, 2, 3, 5, 6});

    assert(r2i == r2);

    // we can also create a bitmap from a pointer to 32-bit integers
    const uint32_t values[] = {2, 3, 4};
    Roaring r3(3, values);

    // we can also go in reverse and go from arrays to bitmaps
    uint64_t card1 = r1.cardinality();
    uint32_t *arr1 = new uint32_t[card1];
    r1.toUint32Array(arr1);
    Roaring r1f(card1, arr1);
    delete[] arr1;

    // bitmaps shall be equal
    assert(r1 == r1f);

    // we can copy and compare bitmaps
    Roaring z(r3);
    assert(r3 == z);

    // we can compute union two-by-two
    Roaring r1_2_3 = r1 | r2;
    r1_2_3 |= r3;

    // we can compute a big union
    const Roaring *allmybitmaps[] = {&r1, &r2, &r3};
    Roaring bigunion = Roaring::fastunion(3, allmybitmaps);
    assert(r1_2_3 == bigunion);

    // we can compute intersection two-by-two
    Roaring i1_2 = r1 & r2;

    // we can write a bitmap to a pointer and recover it later
    uint32_t expectedsize = r1.getSizeInBytes();
    char *serializedbytes = new char[expectedsize];
    r1.write(serializedbytes);
    // readSafe will not overflow, but the resulting bitmap
    // is only valid and usable if the input follows the
    // Roaring specification: https://github.com/RoaringBitmap/RoaringFormatSpec/
    Roaring t = Roaring::readSafe(serializedbytes, expectedsize);
    assert(r1 == t);
    delete[] serializedbytes;

    // we can iterate over all values using custom functions
    uint32_t counter = 0;
    r1.iterate(
        [](uint32_t value, void *param) {
            *(uint32_t *)param += value;
            return true;
        },
        &counter);

    // we can also iterate the C++ way
    counter = 0;
    for (Roaring::const_iterator i = t.begin(); i != t.end(); i++) {
        ++counter;
    }
    // counter == t.cardinality()

    // we can move iterators to skip values
    const uint32_t manyvalues[] = {2, 3, 4, 7, 8};
    Roaring rogue(5, manyvalues);
    Roaring::const_iterator j = rogue.begin();
    j.equalorlarger(4);  // *j == 4
    return EXIT_SUCCESS;
}

```



# Building with cmake (Linux and macOS, Visual Studio users should see below)

CRoaring follows the standard cmake workflow. Starting from the root directory of
the project (CRoaring), you can do:

```
mkdir -p build
cd build
cmake ..
cmake --build .
# follow by 'ctest' if you want to test.
# you can also type 'make install' to install the library on your system
# C header files typically get installed to /usr/local/include/roaring
# whereas C++ header files get installed to /usr/local/include/roaring
```
(You can replace the ``build`` directory with any other directory name.)
By default all tests are built on all platforms, to skip building and running tests add `` -DENABLE_ROARING_TESTS=OFF `` to the command line.

As with all ``cmake`` projects, you can specify the compilers you wish to use by adding (for example) ``-DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++`` to the ``cmake`` command line.

If you are using clang or gcc and you know your target architecture,  you can set the architecture by specifying `-DROARING_ARCH=arch`. For example, if you have many server but the oldest server is running the Intel `haswell` architecture, you can specify -`DROARING_ARCH=haswell`. In such cases, the produced binary will be optimized for processors having the characteristics of a haswell process and may not run on older architectures. You can find out the list of valid architecture values by typing `man gcc`.

 ```
 mkdir -p build_haswell
 cd build_haswell
 cmake -DROARING_ARCH=haswell ..
 cmake --build .
 ```

For a debug release, starting from the root directory of the project (CRoaring), try

```
mkdir -p debug
cd debug
cmake -DCMAKE_BUILD_TYPE=Debug -DROARING_SANITIZE=ON ..
ctest
```


To check that your code abides by the style convention (make sure that ``clang-format`` is installed):

```
./tools/clang-format-check.sh
```

To reformat your code according to the style convention (make sure that ``clang-format`` is installed):

```
./tools/clang-format.sh
```

# Building (Visual Studio under Windows)

We are assuming that you have a common Windows PC with at least Visual Studio 2015, and an x64 processor.

To build with at least Visual Studio 2015 from the command line:
- Grab the CRoaring code from GitHub, e.g., by cloning it using [GitHub Desktop](https://desktop.github.com/).
- Install [CMake](https://cmake.org/download/). When you install it, make sure to ask that ``cmake`` be made available from the command line.
- Create a subdirectory within CRoaring, such as ``VisualStudio``.
- Using a shell, go to this newly created directory. For example, within GitHub Desktop, you can right-click on  ``CRoaring`` in your GitHub repository list, and select ``Open in Git Shell``, then type ``cd VisualStudio`` in the newly created shell.
- Type ``cmake -DCMAKE_GENERATOR_PLATFORM=x64 ..`` in the shell while in the ``VisualStudio`` repository. (Alternatively, if you want to build a static library, you may use the command line ``cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DROARING_BUILD_STATIC=ON  ..``.)
- This last command created a Visual Studio solution file in the newly created directory (e.g., ``RoaringBitmap.sln``). Open this file in Visual Studio. You should now be able to build the project and run the tests. For example, in the ``Solution Explorer`` window (available from the ``View`` menu), right-click ``ALL_BUILD`` and select ``Build``. To test the code, still in the ``Solution Explorer`` window, select ``RUN_TESTS`` and select ``Build``.

To build with at least Visual Studio 2017 directly in the IDE:
- Grab the CRoaring code from GitHub, e.g., by cloning it using [GitHub Desktop](https://desktop.github.com/).
- Select the ``Visual C++ tools for CMake`` optional component when installing the C++ Development Workload within Visual Studio.
- Within Visual Studio use ``File > Open > Folder...`` to open the CRoaring folder.
- Right click on ``CMakeLists.txt`` in the parent directory within ``Solution Explorer`` and select ``Build`` to build the project.
- For testing, in the Standard toolbar, drop the ``Select Startup Item...`` menu and choose one of the tests. Run the test by pressing the button to the left of the dropdown.


We have optimizations specific to AVX2 and AVX-512 in the code, and they are turned dynamically based on the detected hardware at runtime.


## Usage (Using `conan`)

You can install pre-built binaries for `roaring` or build it from source using [Conan](https://conan.io/). Use the following command to install latest version:

```
conan install --requires="roaring/[*]" --build=missing
```

For detailed instructions on how to use Conan, please refer to the [Conan documentation](https://docs.conan.io/2/).

The `roaring` Conan recipe is kept up to date by Conan maintainers and community contributors.
If the version is out of date, please [create an issue or pull request](https://github.com/conan-io/conan-center-index) on the ConanCenterIndex repository.


## Usage (Using `vcpkg` on Windows, Linux and macOS)

[vcpkg](https://github.com/Microsoft/vcpkg) users on Windows, Linux and macOS can download and install `roaring` with one single command from their favorite shell.

On Linux and macOS:

```
$ ./vcpkg install roaring
```

will build and install `roaring` as a static library.

On Windows (64-bit):

```
.\vcpkg.exe install roaring:x64-windows
```

will build and install `roaring` as a shared library.

```
.\vcpkg.exe install roaring:x64-windows-static
```

will build and install `roaring` as a static library.

These commands will also print out instructions on how to use the library from MSBuild or CMake-based projects.

If you find the version of `roaring` shipped with `vcpkg` is out-of-date, feel free to report it to `vcpkg` community either by submiting an issue or by creating a PR.

# SIMD-related throttling

Our AVX2 code does not use floating-point numbers or multiplications, so it is not subject to turbo frequency throttling on many-core Intel processors.

Our AVX-512 code is only enabled on recent hardware (Intel Ice Lake or better and AMD Zen 4) where SIMD-specific frequency throttling is not observed.

# Thread safety

Like, for example, STL containers, the CRoaring library has no built-in thread support. Thus whenever you modify a bitmap in one thread, it is unsafe to query it in others. However, you can safely copy a bitmap and use both copies in concurrently.

If you use  "copy-on-write" (default to disabled), then you should pass copies to the different threads. They will create shared containers, and for shared containers, we use reference counting with an atomic counter.



To summarize:
- If you do not use copy-on-write, you can access concurrent the same bitmap safely as long as you do not modify it. If you plan on modifying it, you should pass different copies to the different threads.
- If you use copy-on-write, you should always pass copies to the different threads. The copies and then lightweight (shared containers).

Thus the following pattern where you copy bitmaps and pass them to different threads is safe with or without COW:

```C
    roaring_bitmap_set_copy_on_write(r1, true);
    roaring_bitmap_set_copy_on_write(r2, true);
    roaring_bitmap_set_copy_on_write(r3, true);

    roaring_bitmap_t * r1a = roaring_bitmap_copy(r1);
    roaring_bitmap_t * r1b = roaring_bitmap_copy(r1);

    roaring_bitmap_t * r2a = roaring_bitmap_copy(r2);
    roaring_bitmap_t * r2b = roaring_bitmap_copy(r2);

    roaring_bitmap_t * r3a = roaring_bitmap_copy(r3);
    roaring_bitmap_t * r3b = roaring_bitmap_copy(r3);

    roaring_bitmap_t *rarray1[3] = {r1a, r2a, r3a};
    roaring_bitmap_t *rarray2[3] = {r1b, r2b, r3b};
    std::thread thread1(run, rarray1);
    std::thread thread2(run, rarray2);
```

# How to best aggregate bitmaps?

Suppose you want to compute the union (OR) of many bitmaps. How do you proceed? There are many
different strategies.

You can use `roaring_bitmap_or_many(bitmapcount, bitmaps)` or `roaring_bitmap_or_many_heap(bitmapcount, bitmaps)` or you may
even roll your own aggregation:

```C
roaring_bitmap_t *answer = roaring_bitmap_copy(bitmaps[0]);
for (size_t i = 1; i < bitmapcount; i++) {
  roaring_bitmap_or_inplace(answer, bitmaps[i]);
}
```

All of them will work but they have different performance characteristics. The `roaring_bitmap_or_many_heap` should
probably only be used if, after benchmarking, you find that it is faster by a good margin: it uses more memory.

The `roaring_bitmap_or_many` is meant as a good default. It works by trying to delay work as much as possible.
However, because it delays computations, it also does not optimize the format as the computation runs. It might
thus fail to see some useful pattern in the data such as long consecutive values.

The approach based on repeated calls to `roaring_bitmap_or_inplace`
is also fine, and might even be faster in some cases. You can expect it to be faster if, after
a few calls, you get long sequences of consecutive values in the answer. That is, if the
final answer is all integers in the range [0,1000000), and this is apparent quickly, then the
later `roaring_bitmap_or_inplace` will be very fast.

You should benchmark these alternatives on your own data to decide what is best.

# Wrappers

## Python
Tom Cornebize wrote a Python wrapper available at https://github.com/Ezibenroc/PyRoaringBitMap
Installing it is as easy as typing...

```
pip install pyroaring
```

## JavaScript

Salvatore Previti  wrote a Node/JavaScript wrapper available at https://github.com/SalvatorePreviti/roaring-node
Installing it is as easy as typing...

```
npm install roaring
```

## Swift

Jérémie Piotte wrote a [Swift wrapper](https://github.com/RoaringBitmap/SwiftRoaring).


## C#

Brandon Smith wrote a C# wrapper available at https://github.com/RogueException/CRoaring.Net (works for Windows and Linux under x64 processors)


## Go (golang)

There is a Go (golang) wrapper available at https://github.com/RoaringBitmap/gocroaring

## Rust

Saulius Grigaliunas wrote a Rust wrapper available at https://github.com/saulius/croaring-rs

## D

Yuce Tekol wrote a D wrapper available at https://github.com/yuce/droaring

## Redis

Antonio Guilherme Ferreira Viggiano wrote a Redis Module available at https://github.com/aviggiano/redis-roaring

## Zig

Justin Whear wrote a Zig wrapper available at https://github.com/jwhear/roaring-zig


# Mailing list/discussion group

https://groups.google.com/forum/#!forum/roaring-bitmaps

# Contributing

When contributing a change to the project, please run `tools/clang-format.sh` after making any changes. A github action runs on all PRs to ensure formatting is consistent with this.

# References about Roaring

- Daniel Lemire, Owen Kaser, Nathan Kurz, Luca Deri, Chris O'Hara, François Saint-Jacques, Gregory Ssi-Yan-Kai, Roaring Bitmaps: Implementation of an Optimized Software Library, Software: Practice and Experience Volume 48, Issue 4 April 2018 Pages 867-895 [arXiv:1709.07821](https://arxiv.org/abs/1709.07821)
-  Samy Chambi, Daniel Lemire, Owen Kaser, Robert Godin,
Better bitmap performance with Roaring bitmaps,
Software: Practice and Experience Volume 46, Issue 5, pages 709–719, May 2016  [arXiv:1402.6407](http://arxiv.org/abs/1402.6407)
- Daniel Lemire, Gregory Ssi-Yan-Kai, Owen Kaser, Consistently faster and smaller compressed bitmaps with Roaring, Software: Practice and Experience Volume 46, Issue 11, pages 1547-1569, November 2016 [arXiv:1603.06549](http://arxiv.org/abs/1603.06549)
- Samy Chambi, Daniel Lemire, Robert Godin, Kamel Boukhalfa, Charles Allen, Fangjin Yang, Optimizing Druid with Roaring bitmaps, IDEAS 2016, 2016. http://r-libre.teluq.ca/950/